Mephisto

"The evil of Mephisto, Lord of Hatred, was so pervasive that even after he had been defeated and entombed in a soulstone, his demonic essence oozed upwards into Travincal and corrupted the Zakarum priests. Though he fell to the same heroes who killed his brothers, I fear for us should he ever return."

As with all of demonkind, Mephisto warred against the High Heavens in the Eternal Conflict. One of these battles bore angels right into the heart of his lair, making an attack against Mephisto himself. One of the angels managed to draw blood, causing it to spill onto the ground. This led to the creation of the Magma Demons, who rose up to defend their master and drove the angels back.[1]

Mephisto and his brothers almost achieved victory against the High Heavens at the Fifth Battle of the Diamond Gates. However, confident of victory, the Primes began arguing over who would get the spoils of war, and thus, their attack failed.[3]

"Cursed am I to lead an army of the blind. They do not perceive that the angels are fleeing this realm, and the ones they find are merely trapped or lost. A great change is upon us. Withdraw from the fields, my brothers. Some battles can only be won with words."

— Mephisto, upon seeing the signs of the Worldstone's disappearance.(src)

Mephisto's visage

While leading his forces on the battlefields of Pandemonium, Mephisto noticed that the angels were withdrawing. He ordered his forces to withdraw so he could analyze the situation. Baal, losing patience, stormed the Pandemonium Fortress and discovered that the Worldstone was missing.[4] Thus, the Eternal Conflict ground to a halt. Eventually, tales of demons summoned into a new realm and a new people reached the ears of the Prime Evils. They sensed within humanity the dormant powers of their nephalem forefathers, and thus resolved to corrupt humanity into a weapon to use against the High Heavens. So it was that Mephisto and his brothers cast their influence into mortal minds, spreading their ideas across Sanctuary. Their whispers led to the creation of the Triune, where each Prime Evil took on the role of a seemingly compassionate deity. Mephisto took on the persona of Mefis, Spirit of Love. Their actions were countered by the rogue angel Inarius, who formed the Cathedral of Light to counter their influence. Thus began the Sin War, as the Prime Evils and Inarius secretly vyed for influence over humanity.[2]

The Sin War ended with a final battle between the forces of Heaven, Hell, and the Edyrem, after which Mephisto met with the Angiris Council. Mephisto offered to let Sanctuary be untouched by either angel or demon to see what the children may yet become on their own for good or ill. It was agreed that Mephisto cast his mark on the ruins of the Cathedral of Light to seal the flux between worlds and in return, Mephisto was given Inarius. It was agreed that humanity be allowed to find its own path, free of the interference from angels and demons.[5]

In the millennia following the Sin War, the Lesser Evils grew discontent, believing that the Prime Evils had forsaken the Eternal Conflict to focus on humanity. The four Lesser Evils rose up against the Primes, and despite the efforts of Mephisto and his brothers, they were cast out of Hell into the mortal realm, in what would become known as the Dark Exile. In response to the most evil of beings walking Sanctuary, the ArchangelTyrael rallied several of the disparate Mage Clans into an alliance known as the Horadrim, and gave them the soulstones to bind the Three forever. In truth, this series of events had been masterminded by the Prime Evils. Through the soulstones they would corrupt, they could corrupt the Worldstone itself and with it, all of humanity. A new army to be used against the forces of Heaven.[2]

At some point during the Exile, Mephisto was present in Aranoch. He bound the spirits of demons into the mummies that slept beneath the sands of Lut Gholein, hordes of undead emerging to bring woe to the living.[6]

Mephisto

Mephisto was the first of the Three to be captured. During their hunt for him, the Horadrim led an army against his Fortress of Bone, but the common soldiers found themselves hard pressed to advance against the seemingly endless tides of undead that he summoned, and were nearly overwhelmed.[1] Eventually, Mephisto was found in or around one of the urban centers of Kehjistan. The fight cost many innocent lives, but eventually, the Horadrim succeeded in defeating the Lord of Hatred and imprisoning his essence inside the soulstone. It was then entrusted to the Zakarum priests and kept sealed in the Guardian Tower of the Temple of Light in Travincal.[7]

"The skies shall rain fire, and the seas will become as blood. The righteous shall fall before the wicked, and all of Creation shall tremble before the burning standards of Hell!"—Mephisto[8]

Mephisto

Over the generations, Mephisto was able to corrupt the High Council of Zakarum, and the body became a mockery of its former glory.[7] The first signs of this were as early as the 11th century. Two centuries after this,[9] Mephisto cemented his control over the Church.[10] He had been able to overcome the soulstone enough to have the Zakarum priests to work spells to shatter the soulstone into seven shards, breaking the mystic seal and freeing him.[11] The Que-HeganKhalim proved immune to his corruption, so Mephisto had the priesthood slay and dismember him. The priest Sankekur became the new Que-Hegan and consequently, Mephisto's embodiment on the mortal plane. The corrupted High Council fashioned the Compelling Orb to control the rest of the Zakarum faithful and used their powers to conceal the lair of their master. Years passed,[7] and eventually, Lazarus was sent west to reawaken Diablo.[2]

Mephisto possessing Sankekur

Thus, Diablo arrived in the form of the Dark Wanderer, with Baal at his side. The two entered the temple's innermost chamber where Mephisto's soulstone was kept, and released him. Mephisto possessed Sankekur (already under Mephisto's control), whose body was twisted to represent Mephisto's hideous visage. After nearly three centuries, the Prime Evils were united. Within the chamber, the Three devised a final stratagem to reclaim the Burning Hells and claim vengeance upon those who overthrew them, along with enslaving humanity to their will. Diablo, assuming his true form, crossed through the Infernal Gate into Hell to rally those still loyal to the Three. Baal began his journey north to corrupt the Worldstone while Mephisto remained behind, bent on destroying anything that could oppose their plan.

It wasn't long before a group of mortal heroes arrived intent on doing such a thing. In the fevered combat that followed, Mephisto worked diligently to turn his foes' own anger and distrust against them. But despite the long hunt and many hours of battle, the heroes defeated Mephisto and imprisoned his essence within his soulstone. The artifact was later destroyed at the Hellforge, which would, in theory, cast his spirit into some unseen netherworld.[2]

Mephisto's essence ended up in the Black Soulstone, as per the machinations of Adria.[12] He would briefly be merged into Diablo as a single Prime Evil,[3] but Diablo was defeated by a new hero and the Great Evils were drawn back into the Black Soulstone, their souls screaming for release.[13] Because of Malthael, the stone was destroyed, and Diablo was freed,[14] still containing Mephisto's essence and those of the other Evils.[15]

"Adventurers fighting in the Durance of Hate may have spotted strange, ghost-like creatures. These "Evil Forces" guard Mephisto and the Infernal gate to the Pandemonium Fortress. Evil Forces can attack and kill those who dare to stick around after Mephisto's demise. The most skilled and tenacious warriors might be able to kill an Evil Force, however, they will discover that the reward is not worth the effort. Some speculate that Evil Forces have some other purpose such as to reveal the way to a hidden world. However, they are simply mindless pawns of Mephisto, like many of the people of Kurast."

Spirits rise from the earth to attack players.

Mephisto can be found on the third level of the Durance of Hate. However, before you can get to him you still have to battle a score of Bloodlords and additional Council Member bosses. You can get to Mephisto either by taking the left or the right way around the pool of blood; both rooms contain a Unique Council Member boss.

Mephisto has a range of abilities he will use against the player: several Lightning based skills such as Lightning and Charged Bolt, a Poison Nova spell and several Cold based skills like Frost Nova. Apart from these abilities, Mephisto has an extremely powerful missile attack that looks like a blazing white orb (referred to as a 'Skull missile' by Blizzard) that can kill most Mercenary units or minions and take away an enormous chunk out of the player's health. Therefore, it is best to stay close to Mephisto. His melee damage isn't very high, though your health can drop steadily if Mephisto combines his Poison Nova and Frost Nova skills. Having enough Cold Resistance and Lightning Resistance once again limits the damage done. In Nightmare and Hell difficulty, Mephisto is immune to life and mana leech (unless Life Tap is cast) so it is best to stock op on health, mana and rejuvenation potions before battling him.

Evil Force

It might also be a good idea to battle Mephisto in one of the rooms on the left or right in order to avoid a trap: in the backroom where Mephisto stands there are restless spirits that sometimes rise up and lash out at players who are in range. These spirits can be killed, but it's very hard to hit them and the experience reward is small and the loot nonexistent, therefore, it's best to avoid them.

The easiest method to defeat Mephisto is to first draw Mephisto's attention by approaching him very slowly, then retreating to the central room that is separated from Mephisto by the pool of blood. Even though he should be perfectly capable of gliding past the pool the same way the player did, his AI, which forces him to only move in the direct direction of the player's position, does not allow him to do this. Mephisto can be defeated eventually with either ranged weapons or missile or area-of-effect spells, and the player can do this with hardly any fear of death as long as he or she stays far enough from him so that he cannot cast spells at the player, although mercenaries and summoned minions may approach too near and be blasted with his magic within seconds. Just be careful not to approach Mephisto too much by any mistake.

A Volcano erupts from Mephisto's body.

When Mephisto dies, a volcano erupts from his body; it doesn't do any damage, however. Now that Mephisto is dead, you can search his room for stashes of gold. Note that he also dropped his Soulstone: this item is needed in a quest in Act IV. If you don't pick it up, Deckard Cain will give it to you later. Walk towards the portal, and a bridge made of bones and skulls should rise from the pool of blood. Cross the small bridge and enter the Infernal Gate to complete Act III.

"Cursed am I to lead an army of the blind; they do not perceive that the angels are fleeing this realm, and the ones they find are merely trapped or lost! A great change is upon us; withdraw from the fields, my brothers... ... some battles can only won with words..."

"You're too late! [laughs]" (upon approaching Mephisto)

"My brothers have escaped you!" (upon approaching Mephisto)

"My brothers, at long last we stand reunited. The Infernal Gate has been prepared, and the time of our final victory is at hand. Let the way to Hell be opened!" (cinematic)

Mephisto's death animation

"And the Evil that was once vanquished shall rise anew. Wrapped in the guise of man, shall he walk amongst the innocent, and Terror shall consume they that dwell upon the Earth. The skies shall rain fire, and the seas will become as blood. The righteous shall fall before the wicked, and all of Creation shall tremble before the burning standards of Hell!" (cinematic)

"The Gate stands ready!" (cinematic)

"Now my young brother, the time has come to assume your true form! Arise Diablo, Lord of Terror!" (cinematic)

Many claim that Mephisto is the most intelligent of the Prime Evils. It is said that Mephisto was most adept at pitting his brothers against each other. Diablo and Baal chafed at his manipulations, but more often than not they complied. Deckard Cain speculated that this was because Mephisto provided them with ample opportunities to pursue their ambitions. Perhaps because of this, Mephisto is seen by some to be a unifier and great tactician. It was Mephisto's greatest ambition to pit entire societies against each other, to turn brother against brother, to seed discord and distrust wherever he could. Mephisto viewed hatred as a tool, though one to be wielded with precision. He loathed all,[2] including the nephalem[17] but his greatest hate was reserved for angels. And so the inhabitants of Sanctuary were seen by him as weapons to be forged in his likeness and directed towards the High Heavens.[2]

Mephisto stands at 20 feet tall.[7] He possesses "foul blood"[1] and his voice itself is painful to hear[8] The undead are the minions of Mephisto.[1]

"Mephisto" is a variation of the name Mephistopheles, the devil figure in the Faust legend, often used as an alternative name for Satan or Lucifer. It may also be derived from the Hebrew words Mephis (מפיץ) which means "Distributor" and Tophel (תפל) which means "Falsehood". I.e. Distributor of superstitions.

"Odium" refers to "intense hatred or dislike," usually directed towards a single individual. "Odium theologicum" is a related term that applies to hatred generated by disputes over theology.

Mephisto's redesign (or true form) in the Book of Cain features horns that are more similar to Diablo's than the ones he had when possessing Sankekur.